Generally, unlike primary batteries which can not be charged, secondary batteries are rechargeable and are widely used in various fields and devices such as cellular phones, laptop computers, or camcorders. Examples of currently commercialized secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries, and batteries such as metal-air batteries, all-solid-state batteries, sodium-based batteries, or magnesium batteries have been of great interest and developed as next-generation batteries.
Among such various secondary batteries, lithium secondary batteries are freely rechargeable because of substantially no memory effect compared with nickel-based secondary batteries, and thus have a very low self-discharge rate and high energy density, and owing to these merits, there has been high interest in lithium secondary batteries.
In general, such a lithium secondary battery uses a lithium-based oxide as a positive electrode active material and a carbonaceous material as a negative electrode active material. In addition, such a lithium secondary battery is formed by accommodating a positive electrode plate coated with a positive electrode active material and a negative electrode plate coated with a negative electrode active material in a case together with an electrolyte, and a typical example of electrolytes is a liquid electrolyte which is also called “an electrolytic solution.”
Secondary batteries including a liquid electrolyte are widely used owing to various advantages such as ease of handling and manufacturing, and high electrical conductivity and stable performance at room temperature. However, liquid-electrolyte batteries may have problems such as electrolytic solution leakage or gas generation, and thus the safety of such secondary batteries may be significantly lowered because of the possibility of explosions, catching on fire, discharge of noxious gas, etc.
Therefore, all-solid-state batteries using a solid electrolyte have been of great interest and developed to prevent problems such as electrolytic solution leakage and gas generation and guarantee safety. In particular, electric vehicles or power storage devices, such as electric charging stations for electric vehicles or power storage devices for smart grids, may require a large number of secondary batteries, and thus there is increasing interest in stable all-solid-state batteries. However, such all-solid-state batteries have low ionic conductivity at room temperature and may thus have a relatively high operating temperature compared with liquid-electrolyte batteries. Therefore, when all all-solid-state batteries are used to constitute battery modules, it is necessary to set relatively high temperature conditions compared with the case of using liquid-electrolyte batteries.
In general, however, battery modules of the related art are made using liquid-electrolyte batteries and thus have structures not suitable for all-solid-state batteries.
In particular, most battery modules use cartridges as structures for easily stacking and storing a plurality of pouch-type secondary batteries, protecting the secondary batteries from external impacts, and preventing relative movement of the secondary batteries. Such cartridges may be expressed in various other terms such as a stacking frame and may be configured to be stacked in a direction, for example, a vertical direction. Secondary batteries may be accommodated in inner spaces formed in stacked cartridges. In general, cartridges may have various structures to decrease the temperature of secondary batteries accommodated therein. For example, cartridges may include plate-type cooling fins or openings formed therebetween to introduce ambient air. The reason for this is that liquid-electrolyte secondary batteries included in battery modules have relatively low performance and serious safety problems such as explosions or catching on fire at temperatures much higher than the room temperature.
On the contrary, the performance of secondary batteries such as all-solid-state batteries may be poor at room temperature but may be improved at temperatures higher than the room temperature. Therefore, it is not suitable to use structures of battery modules of the related art such as a cartridge structure for all-solid-state batteries.